In erecting and maintaining wind power plants, some tasks require that the wind rotor should be rotated into certain prescribed positions. For example, access to the rotor hub through an access opening is only possible for a service technician if the rotor is in a particular position, so that the access opening is in overlap with a manhole on the end of the pod. In the course of some tasks, it is also necessary to turn the wind rotor several times, e.g. when changing the oil. During this process, the rotor blade has to be moved into a particular position to drain the oil from an actuating drive of said rotor blade, and this has to be repeated successively for all the rotor blades of the wind rotor. Various approaches have been disclosed in the prior art for facilitating this activity.
The first and oldest approach is to turn the wind power plant by hand, with a fitter gripping an element of the rotor shaft and in this way turning it. Whereas this can lead to quite reasonable results in the case of small wind power plants with a correspondingly small wind rotor, this is too laborious and time-consuming for larger modern wind power plants. Irrespective of this, it represents a considerable risk to the fitter because of the direct contact with the rotor shaft.
Relatively large wind power plants are often provided with a transmission for stepping up the rotational speed of the wind rotor, which tends to be somewhat low for aerodynamic reasons, to drive the generator. An additional flange, on which an adjusting motor is arranged, can be provided on this transmission. The gearset in the transmission is acted upon by actuating the adjusting motor, and the rotor shaft is thus turned slowly. This arrangement has the disadvantage that the transmission is subjected to an additional load. Not infrequently, this necessitates reinforcements. Moreover, there are certain concerns relating to the reliability of the transmission since the transmission is subjected to a load counter to the main load flow direction thereof owing to the influence of the adjusting motor.
The problems associated with the transmission are avoided in another approach, in which the gearset for the actuating drive is relocated out of the transmission. For this purpose, a separate gearwheel, in which the adjusting drive engages, is provided on the rotor shaft. In order to limit requirements in terms of costs and installation space to which an additional gearwheel of this kind gives rise, there is a known practice of designing the gearwheel as a specially designed brake disk with correspondingly shaped external teeth. However, one disadvantage of this solution is that the brake disk per se is a low-cost mass produced product and is converted into an expensive special component by the external teeth required. Moreover, it is possible to retrofit existing wind power plants only with difficulty.